I did some research for you and found the Safety 1st 360 Cool Mist Humidifier is not antimicrobial.
It did get a lot of wonderful reviews from customers and I personally know someone who is still using this and is very pleased.
I decided to also include links to top consumer and/or blog pages that may have more information on which baby humidifers have what you are looking for:
Baby Gear Labm.babygearlab.com/Humidifier-Reviews
Consumer Report (like this one a lot and is the one I found your answer on) consumerreports.org/humidifiers/Humidifier-Clean-Air-Tests/
There is several mom blogs with wonderful suggestions, if you would like more links let me know. Anymore questions, concerns, advise, research, etc... just click on the link below my name and add me as your very own personal shopper. You Will receive personal one on one attention and my personal number and email to get in touch with me quickly. I am also an excellent bargain hunter.
I hope you have a wonderful morning, Sheila.
Personal Shopper syw.co/AngelDye